1. Field of the Invention
This invention concerns a nutation damper which exerts a damping force on the nutation of high-speed spinning bodies such as flywheels used in magnetic bearings and gyroscopes.
2. Discussion of Background
Although flywheels (reaction wheels) and gyroscopes are generally used for attitude control of satellites, an intrinsic oscillation called nutation occurs in this type of high-speed spinning body due to the gyro effect. This nutation is manifested as a wobbling of the spin axis of the spinning body. If the speed of spin of the spinning body is taken as f.sub.s, the moment of inertia of the spinning body about the spin axis is taken as I.sub.p and the moment of inertia of the spinning body about an axis orthogonal to the spin axis is taken as I.sub.d, the frequency of nutation f.sub.n is EQU f.sub.n =(I.sub.p /I.sub.d)f.sub.s
And, in high-speed flywheels and gyroscopes which can direct the spin axis to any given direction the, damping force for nutation occurring due to external disturbance is extremely small. Thus nutation cannot converge and waddling about the spin axis occurs. For this reason, in the case of satellites which use high-speed spinning bodies for attitude control, there was the disadvantage that a slow motion was caused or the immobility of the gyroscope was impaired.
When the speed of spin of the spinning body is small there is hardly any problem with the nutation described above but, as the spin speed of the spinning body becomes greater, the problem becomes more serious. In the case of prior flywheels and gyroscopes, almost no consideration was given to nutation, but as the speed of spinning bodies has become greater, counter-measures for nutation have become important.